Safety device for cranes and the like



Feb. 11, 1936. A. F. NASH SAFETY DEVICE FOR CRANES AND THE LIKE FiledDec. 22, 1931 8 Sheets-Sheet 1 Feb. 11, 1936. A.'F. NASH 2,030,529

SAFETY DEVICE FOR CRANES AND THE LIKE Filed Dec. 22, 1951 a Sheets-Sheet2 Fb; 11, 1936.- A. F. NASH 2,030,529

, 'SAFETY DEVICE FOR CRANES AN]? THE LIKE Filed Dec. 22, 1931s-sneets-snet s Feb. 11,1936. AJF. NASH 2,030,529.

SAFETY DEVICE FOR CRANES AND IHE LIKE Filed Dec. 22, 19:51 8Sheets-Sheet 4,,

Feb. 11, 1936. A. F. NASH SAFETY DEVICE FOR CRANES AND THE LIKE FiledDec. 22, 1931 8 Sheets-Sheet 5 Feb. 11, 1936. A. F. NASH SAFETY DEVICEFOR CRANES AND THE LIKE Filed Dec. 22, 1931 8 Sheets-Sheet 6 Feb. 11,1936. A. F. NASH 2,030,529

SAFETY DEVICE FOR CRANES AND THE LIKE Filed Dec. 22, 1951 a Sheets-Sheet7 Feb. 11, 1936. I A. F. NASH 2,030,529

SAFETY DEVICE FOR CRANES AND THE LIKE Filed Dec. 22, 1931 8 Sheets-Sheet8 pave/r724 Patented Feb. 11, 1936 PATENT, OFFICE";-

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Archibald Nash, Kingston Hill, England Application December 22, 1931,Serial No. 582,866 In Great Britain December 29, 1930 3 Claims. (L116-114) This invention relates to lifting devices and particularly tocranes, derricks, shear legs and the like lifting devices provided withlufling gear or otherwise with means adapted to provide a.

varying radius of lift andhas for its object to provide improved meansadapted to operate to ensure that the limits of safety of the devicewill not be exceeded as, for instance, by giving a visible, audible orother warning signal to the in operator of the device with or withoutsimultaneously actuating means for positively deferring or interruptingthe operation of the lifting device when the safe load is exceeded.

According to the invention the safety means comprises. two independentlymoving elements, one actuated by the magnitude of the load to be raised,the other actuated in accordance with the angle of inclination of thejibor its equivalent or otherwise in accordance with variations in theradius of lift, said elements being associated one with the other insuch manner that the relation between the positions they are caused toassume will operate to indicate when the lifting device is overloadedand/or to indicate the relation between the magnitude of the load andthe permissible limit of loading.

At this point it may be mentioned that the invention extends not only tocranes provided with jibs or the like, the inclination of which isadapted to be varied, but also tohammer-head and shipyard cranes andother lifting devices in which, for instance, the crane hook or itsequivalent is arranged on a carriage adapted to travel on a cantileveror a similar structure.

Thus in accordance with the invention, an indicator adapted to be movedrelatively to a scale in accordance with the angle of inclination of thejib or its equivalent or otherwise in accordance with variations in theradius of lift and which may directly indicate the magnitude of theangle 'is asceiated with a second indicator actuated solely orprincipally by the weight of the load being raised in such manner thatthe two indicators will cooperatein showing when the safe load isexceeded.

' For instance, an indicator adapted-to be moved in accordance with thevariation of the angle of inclination of the jib or otherwise inaccordance with variation in the radius of lift may be proto vided withan index cooperating with a scale and adjacent thereto and cooperatingwith the index there may be arranged a second indicator adapted to beinfluenced by the magnitude of the load in such manner as to cause asecond scale, with di- 55 visions marked "Safe", "Maximum", and Danger"to be moved relatively to the main scale and to the index. i

Alternatively, the indicator adapted to be moved in accordance with thevariation in the radius of lift may be provided with an index 5 plate orscale having divisions marked Safe, Maximum and Danger and with thisindicator there may be associated a scale marked with divisions adaptedto indicate the magnitude of the load being raised and adJacent to theilrsto mentioned indicator there may be arranged to cooperate with thescale a second indicator adapted to be moved over the scale inaccordance with the magnitude of the load.

The invention will be described further in de- 15 tail and by way ofexample with reference to the accompanying drawings, in which:-

Figure 1 is a view of one construction,

Figure 2 being a view of a detail thereof;

Figures 3, 4, 5, 6, 7, and 8 are fragmentary views :0 illustratingvarious alternative means whereby the eil'ect of the load on the burdenrope or chain may be applied to a device for indicating the magnitude ofthe load such, for instance, as is illustrated in Figures 1 and 2; 25

Figure 9 illustrates an alternative construction in which the eifect ofthe load is applied through the jib to hydraulic balancing means,

Figures 10, 1i, and 12 illustrate alternative hydraulic balancing meanswhich may be employed; 30

Figures 13, 14, 15, and 16 illustrate fin-ther arrangements in which theeffect of the load is applied to the base of the jib;

Figure 17 illustrates one application of the invention to a derrick; v35 Figure 18 is a view in elevation and partly in section of anotherconstruction adapted more particularly for application to lumng cranes;

Figure 19 is a view in front elevation showing the indicator dialthereof; 40

Figure 20 isa dissected view in elevation showing certain elements ofthe construction illustrated in the preceding figures;

Figure 21 is a corresponding plan view;

Figure 22 is a view of certain other details 45 which in Figure 18 aresuperimposed on the details shown in Figure 20,

Figure 23 being a plan view corresponding with Figure 22. Figures 24,25, and 26 illustrate three further constructions of jib crane inaccordance with the invention, and

Figures 27 and 28 are, respectively, a view in side elevation and afragmentary view partly in section of a cantilever crane embodying theinvention.

Referring to Figures 1, 3, 4, 5, 6. 7, 8, 9, 10, 11, l2, 13, 14, 15, 16,17, 24, 25, and 26. I represents the jib which is pivotally secured, inthe case of the constructions shown in Figures 1,-7, 8, 9, 10, 11, 12,13, 14, 24, 25, and 26, to the base plate 2.

In Figures 1, 3, 4, 5, 6, 7, 8, 24, 25, and 26, 3 indicates the pulleyat the head of the jib, while 4 indicates the burden rope.

In the case of the constructions illustrated in Figures 1 to 5 and 26,means is associated with the pulley itself adapted to be influenced bythe magnitude of the load or the overturning moment due to the load andthe angle of inclination of the crane.

For this purpose in the constructions illustrated by Figures v thesleeve 5 in turn eccentrically mounted on the pin 5 secured in the sidesof the jib. with this sleeve is connected an arm I which, in the case ofthe construction illustrated in Figures 1 and 26, is connected with apiston 8 working in a chamber 9. In the case of the construction shownin Figure 3, the arm is connected by a link ill with the flexible wallll of the chamber In the case of the constructions shown in Figures 4and 5, the pulley is mounted in a bearing i3 which, in the case of theconstruction shown in Figure 4, is connected with a piston l4, slidablymounted in the chamber l5, while in the case of the construction shownin Figure 5 the bearing is connected with the flexible wall Ii of thechamber i1.

In the construction shown in Figure 6, the lifting rope or burden ropeis taken over a second pulley I8 and under a third pulley [9 which isplvotally mounted in the lever 20, in turn pivotaily mounted about thepin 2| secured to the jib of the crane and the end of the lever inquestion is connected by the rod 22 with a piston 23 working in acylinder 24 while in the case of the construction shown in Figure 'l thedrum 25 about which the rope or chain is wound is journalled in asliding bearing 28 connected by the rod 21 with the piston 28 working inthe chamber 29.

In the construction shown in Figure 8, one end of the burden rope isconnected with the lever 30 pivoted at 3i and connected by the rod orlink 32 with the piston 38 slidable within the chamber 34.

In the case of the constructions illustrated by Figures 9, 10, 11, and12, as has been explained, the eflect of the load is applied through theJib of the safety device and in the case of the construction illustratedin Figure 9, the end of the jib forms a piston 35 working in the chamber36 pivotaily connected by the pin 81 with the base of the crane.

In the construction shown in Figure 10, the jib is pivotally connectedby the pin 88 with a piston 39 operating in the chamber 40 while in thecase' of the construction illustrated in Figure 11, in the length of thejib there is interposed a flexible walled chamber 4i, while in the caseof the construction illustrated in Figure 12, a, similarly formedchamber 42 is arranged in the block 43 which forms a pivotal mountingfor the jib.

In the case of the derrick illustrated in Figure 17, the post 44 of thederrick is pivotally connected by the pin 45 with the base plate 46mounted in known manner on the foot-step 41 and the 1, 3, and 26, thepulley is mounted onpost 44 is connected by the rod 48 with the piston49 working in the chamber 50.

In all of the constructions above described the chamber in which thepiston is mounted or, alternatively, what is its equivalent, theflexible walled chamber, is filled with liquid and is connected by aflexible pipe 5| with a piston or diaphragm device of known characteradapted to move an index needle 52 over a scale such as 53 in accordancewith the magnitude of the pressure within the pipe.

With all of the constructions above described there is also associatedmeans, although for convenience it has been omitted from certain of theflgures, adapted to be actuated in accordance with the variation in theangle of inclination of the jib. The character of this means is clearlyshown in Figures 1, 8, 9, and 1'1, and it comprises a link 54 connectedwith the foot of the jib and with a plate 55 pivotally mounted on thepin 55 and provided with a cam slot 51 in which operates a roller 58connected with a lever 59 pivoted on the pin 60 secured to some fixedpoint, the lever being in turn connected, through the link 6i, with atoothed bevel sector 62 rotatable about the pivot 53. This toothedsector is in engagement with a toothed bevel wheel 64 mounted on theshaft 65 and connected with the member 56 carrying the indicator 61marked into divisions inscribed Safe, Max." and Danger".

As will be appreciated in the above constructions the load which isbeing raised will operate to move the index 52 over the scale which mayindicate the dead weight of the load or, alternatively, indicate themagnitude of the overturning moment, while variation in the angle ofinclination of the jib will cause the cam plate 55 to be moved thusmoving the lever 59 about its pivot and thereby causing correspondingmotion of the toothed bevel sector 62 which, in consequence of itsengagement with the toothed bevel wheel 64 will in turn impart motion tothe member 51.

The cam slot will be formed so as to impart appropriate motion to themember 61 in accordance with the variation in the angle of inclinationof the jib so. as to ensure that in all positions of the jib byco-operation of the index 52 with the scale 61, the device will indicatewhether the lifting device is being worked within the limits of safetytaking into account the various factors such as the crushing strength ofthe jib and the stresses set up in the various portions of the crane orthe like whether the maximum load for a particular angle of inclinationis being raised or whether this maximum load is exceeded.

In the case of the constructions illustrated in Figures 13 and 14, thejib is mounted upon a pin 58 in the eccentric 69 which, as shown inFigure 14, is mounted in ball bearings 10.

In the construction illustrated in Figure 16, the post 44 is associatedwith an eccentric, which is journalled in the collar "II in the link I2connected by the pin 13 with the bracket 14 extending from the baseplate 45. I

In each of these constructions the eccentric is provided with an arm 15connected with the rod 15 about which is arranged in compression, thespring II one end of which bears on a washer I8 secured in position onthe rod by nuts iii, the other end of the spring bearing against anabutment provided on the plate M which, in the case of the constructionillustrated in Figure 13, is connected with the jib while in theconstruction illustrated in Figure 14, the plate in question isconnected with the base plate of the crane with ' a,oso,sao

a cam II with which is arranged to co-operate a roller II provided onthe arm II of a bell crank lever. The other arm II of the bell cranklever is extended and is provided with a plate II which is marked Safe,"Maximum" and "Danger", to move this plate relatively to the scale andalso relatively to the arm II.

In Figure 15. which illustrates a construction resembling in certainrespects the construction illustrated in Figures 13 and 14, likereferences indicate like parts. In this construction,however,therodlIisconnectedtoonearmofthe bell crank lever I'I pivoted onthe pin II, the other arm of this lever being connected with the B yrope II.

Referring to Figures 18 to 23, in Figure 18, IIIisacasinghousingtheessentialmechanism of the safety device. In thisconstruction some member subjected to the action of the load, forinstance, an eccentric on which the pulley at the head of the jib ismounted, is connected by a rod ill with the member III slidably mountedbetween guide rollers III.

About an extension I of this member there is arranged a spring III, oneend of which bears against the fixed abutment III, while the other bearsagainst the cupped washer III secured in position by the nuts III. Themember it! is connected by the link. III with the toothed sector IIIwhich is pivoted on the pin Iii and this toothed sector is in engagementwith the bevel wheel III secured to a tubular shaft I mounted inbearings IN, Illa, in the sleeve III which forms an extension of acircular closure'i II for the casing. The circular closure forms part ofthe housing for the indicating mechanism which comprises a dial ill withwhich co-operates the index III secured to the tubular shaft III. Withthe dial also co-operates a disc III marked as shown in Figure 19 intodivisions bearing such inscrMions as Bate working", Maximum and "Danger.This disc is connected to the shaft III rotatably mounted in bearingsIII and "in. On the shaft III there is secured a bevel wheel III whichmeshes with a toothed sector III pivotally mounted on the pin ill andprovided with a roller III in the cam slot III of the sector III whichis pivoted on the pin i2! and is rigidly connected with the pendulumIII, the bob III of which is provided with recesses III and lIIoinwhichwork pistons III and "lo connected by the rods III and i324: with theplate III rlgidlyconnectedtothepost III andtothepin Ill.

The pistons III and "in operating in the recesses which are filled withoil function as dampers.

one end oi the lever II mounted on the pin ll. while the other end ofthe lever is formed as generally by the reference III which. in the caseof the construction illustrated in Figure 24; is arranged adjacent tothe jib head while in the case of the construction illustrated in Figure25', the dvnamometer device is arranged at the base of the Jib. the ropebeing. in this construction, led over a second pulley III adjacent tothe jib head and then down to the dynamometer device.

In both of these constructions the indicator element III, which ismainly influenced by variation in the magnitude of the load, co-operateswith the main scale I and with this scale there is associated a secondindicator element III which is moved relatively to the main scale byvariation in the radius of lift. This indicator element corresponds infunction with the indicator element 61, in the construction shown inFigure l, or the indicator element II, in the constructions shown inFigures 13 to 16, and it is actuated by variation in the angle ofinclination of the jib, as in the case of the construction shown inFigure 1. through the intermediary of a link 54 connecting the foot ofthe jib with the plate II pivotally mounted on the pin it and providedwith a cam slot I! in which operates a roller II connected with a leverII pivoted on the 'pin II secured to some fixed point on the base plateI of the crane, the lever II being connected by the link II with. theextension III of the second indicator element i which is co-axiallymounted with the indicator element III.

In the case of the construction illustrated in Figure 24, motion istransmitted to the indicator element Ill from the lever II through aflexible wire or III commonly called a Bowdcn wire mechanism.

The arrangement illustrated in Figure 26 is more particularly adaptedfor cranes having a long Jib and in this case the thrust from theeccentric sleeve I is transmitted through the lever I to the ram Ioperating in the'cylinder I from which a pipe line ll extends to acylinder I provided with a flexible diaphragm I connected to one end ofa rack I, the other end of the rack being connected with the flexiblediaphragm ill provided-on the cylinder I fromwhichextendsasecondpipeline lllinwhichthefiuidisnotsubiectedtoplessureduetoload,

the pipe lines 5| and I49 running parallel. The rack I46 co-operateswith a pinion I50 on the spindle I6I of the indicator element I52 whichmoves over the scale I55 and with this scale there is arranged toco-operate, as in the previously described constructions, a secondindicator element III which is co-axially mounted with the pinion inquestion. Motion of this indicator element relatively to the scale is,as in the case of the construction illustrated in Figures 24 and 25,effected through the intermediary of a link 64 connecting the foot ofthe jib with the plate 55 pivotally mounted on the pin 56 and providedwith a cam slot 51 in which operates a roller 56 connected with a lever59 pivoted on the pin 66 secured to some fixed point on the base plate 2of the crane, the lever 69 being connected by the link 6| with theextension III of the second indicator element Ill.

Referring to Figure 27 in which a crane of the hammer head or cantilevertype is illustrated, the carriage I54 is arranged to travel along thecantilever I55, the carriage being provided with wheels I56 and in thisconstruction the burden rope I51 is carried over pulleys I58, I 59, asnatch block I66 being arranged in the bight of the rope between thesepulleys and continued over the pulley I6I which is mounted upon aneccentric sleeve I62, the rope extending to the winding drum I63. Theeccentric sleeve I6! is connected with the lever I64 which, in turn, isconnected through the rod I65 with the dynamometer device I66 in suchmanner that the indicator element I61 will be moved over the main scaleI68 by variation in the magnitude of the load raised.

On the carriage I54 there is provided also a grooved wheel I65 engagingthe edge of the spiral formed blade I10 which is connected by arms "I tothe shaft I12 on the end of which is provided a crank I13 connected bythe rod I14 with a second indicator element I15.

' With this construction, as will be appreciated motion or the carriagealong the cantilever will cause rotation of the shaft I12 which, inturn, will cause motion to be imparted to the indicator element I15moving the same over the scale I68 in accordance with variation in theradius of lift.

I claim:

1. A safe load indicator for a, lifting device of the kind having amember to which motion is imparted for varying the radius of lift,comprising a scale bearingmember marked with graduations indicating loadmagnitudes, an indicator be imparted to the cam, a connection betweenthe cam and the indicator element in the form of a scale marked withindications Safe", "Maximum" and Danger" adapted to move the saidindicator element relatively to the scale bearing member in accordancewith variation in the radius of lift, an indicator element in the formof a pointer, a weight sensitive device and an operative connectionbetween said weight sensitive device and the pointer adapted to move thepointer relatively to the scale bearing member in accordancewithvariations in the magnitude of the load being raised.

2. A safe load indicator for a lifting device of the kind having amember to which motion is imparted for varying the radius of lift,comprising a scale bearing member marked with graduations indicatingload magnitudes, an indicator element in the form of a scale marked withindications Safe", Maximum and Danger, a cam pivotally mounted on thelifting device, a connection between the member to which motion isimparted for varying the radius of lift and the cam whereby by suchvariation motion will be imparted to the cam, a connection between thecam and the indicator element in the form of a scale marked withindications Safe", Maximum" and Danger adapted to move the saidindicator element relatively to the scale bearing member in accordancewith variation in the radius of lift, an indicator element in the formof a-pointer, means for moving the pointer relatively to the scalebearing member in accordance with variations in the magnitude .of theload being raised, said means including a pulley, a

flexible member pasing over said pulley and subjected to tension by theload, an eccentric mounting for the pulley, stress receiving meansassociated with the eccentric mounting and means adapted to move thepointer relatively to the scale in accordance with stresses set up inthe stress receiving means by the load.

3. A safe load indicator for a lifting device having a varying radius oflift comprising a pivotally mounted indicator element in the form of ascale marked with indications Safe, Maximum" and "Danger", cam-operatedmeans adapted to move the said indicator element about its pivotalmounting in accordance with variations in radius of lift and anindicator element in the form of a pointer pivotally mounted coaxiallywith respect to the first-mentioned indicator element, a weightsensitive device and an operative connection between said weightsensitive device and the indicator element in the form of a pointeradapted to move the same about its pivotal mounting relatively to theindicator element inthe form of a scale.

ARCHIBALD FRAZER NASH.

